1. Field of the Invention
The present invention relates to an ultrasound diagnosis apparatus which displays an enhanced ultrasound image. The present invention also relates to a method of displaying an enhanced ultrasound image.
2. Discussion of the Background
An ultrasound diagnosis apparatus is known to be advantageous since it can allow to easily displaying, for example, a heartbeat motion or a fetus motion in real time by only applying an ultrasound probe to a body surface of a patient. Also, there is no worry about an X-ray exposure in ultrasound imaging, and thus it is safe for the patient and can be repeated without a risk of the X-ray exposure. Further, an ultrasound diagnosis apparatus can be made compact in size, compared to an X-ray diagnosis apparatus, an X-ray computed tomography (CT) apparatus, a nuclear magnetic resonance imaging apparatus, and the like. Therefore, it is easy to conduct an ultrasound imaging examination at bedside. Although the size of the ultrasound diagnosis apparatus may depend on features equipped in the apparatus, it is nowadays reduced down to a size allowing a user to bring the apparatus one-handed.
As a typical focal medical treatment of the hepatocellular carcinoma, the percutaneous ethanol injection therapy (PEIT), the percutaneous microwave coagulation therapy (PMCT), and the radiofrequency abration (RFA) may often be conducted. For example, in the percutaneous ethanol injection therapy, a paracentesis needle is penetrated towards a tumor under an ultrasound imaging guide. A medical agent is administered to the tumor through the paracentesis needle so as to extinct cancer cells. In the percutaneous microwave coagulation therapy, microwaves are exposed to the tumor and coagulate the tumor so as to extinct cancer cells. In the radio frequency abration, the tumor is heated by the high temperature so as to extinct cancer cells. It is usually quite easy to conduct any of the above medical treatment. In addition, the patient may not suffer a lot from the medical treatment.
Whether the medical treatment has successfully been conducted or not is often ascertained by imaging the patient with a dynamic CT apparatus, the nuclear magnetic resonance imaging apparatus, or the like. These medical imaging apparatuses may also be used to find where the tumor is located before the medical treatment. However, an ultrasound diagnosis apparatus is also used nowadays to ascertain or find the same since the ultrasound diagnosis apparatus has been improved recently and an intravenous contrast agent has been introduced for the ultrasound imaging. In such an enhanced ultrasound imaging technique, for example, blood flow signals may be enhanced and a dynamic state of the blood flow may be evaluated in a cardiac examination or an abdominal organ examination by administering a contrast agent from the vein, as described in Japanese Patent Application Publication No. 2003-153900.
When the enhanced ultrasound imaging technique is used to ascertain whether the medical treatment has successfully been conducted or not, images showing a specific part (typically a part of the tumor) obtained before the medical treatment are usually compared to images showing the same obtained after the medical treatment. For example, when the blood is flowing into the part of the tumor through the blood vessel before the medical treatment, the medical treatment is determined to have successfully been conducted if the blood stops flowing into the part of the tumor through the blood vessel after the medical treatment. If the blood is still flowing into the part of the tumor through the blood vessel after the medical treatment, the medical treatment is determined to have failed and required again.
In the enhanced ultrasound imaging technique, it is important to know a time phase of the ultrasound image data in the process from the administration of the contrast agent. In the case of liver, for example, the contrast agent flows into the hepar artery, the portal vein, and the like. As a result, the blood vessels are enhanced in ultrasound images displayed in a display unit. Such images in which the blood vessels are enhanced may be called vascular images. As time passes, the contrast agent continues to flow into blood capillaries and tissues inside the liver. Accordingly, the liver is enhanced as a whole in ultrasound images displayed in the display unit. Such images in which the blood capillaries and tissues (or the organ like the liver) are enhanced may be called perfusion images.
As described above, images to be displayed changes from the vascular images to the perfusion images according to the time phases in the process from the administration of the contrast agent. Therefore, time phase information and corresponding images are important as diagnosis information. For this reason, the ultrasound diagnosis apparatus capable of the enhanced ultrasound imaging technique often includes an injection timer which measures time elapsed from the administration of the contrast agent. Also as described, it is usually necessary to obtain ultrasound images (or moving images) of before and after the medical treatment in order to ascertain whether the medical treatment has successfully been conducted or not.
In conducting the enhanced ultrasound imaging technique, it maybe necessary to activate the injection timer and also to initiate storage of ultrasound images at the same time as the administration of the contrast agent. Further, after the medical treatment, it may also be necessary to retrieve appropriate enhanced images obtained before the medical treatment from an image file storing ultrasound images. Finally, it may be necessary to display and compare the ultrasound images obtained before and after the medical treatment in accordance with the time phase in the process from the administration of the contrast agent in order to ascertain whether the medical treatment has successfully been conducted or not. Consequently, a user of the ultrasound diagnosis apparatus may be required cumbersome operations from the imaging to the ascertainment.